D-MOSFETs are sometimes used in series to construct a cascode high-frequency amplifier to overcome the loss of:

ANS:C - high input impedance

It's a plastic foam that has been saturated with carbon particles, allowing it to dissipate static charges. Due to the high carbon content, it is usually black in color. It is frequently used for packaging or storing static-sensitive electronic components, such as MOSFET transistors and integrated circuits.